The earliest settlement of South Sulawesi by humans is dated to c. 30,000 BC. No earlier evidence of human occupation has been found, but the island almost certainly formed part of the land bridge used for the settlement of Australia and New Guinea.

In Central Sulawesi there are over 400 granite megaliths, which various archaeological studies have dated to be from 3000 BC to 1300 AD.

The first Europeans to visit the island were Portuguese sailors in 1525, sent from the Moluccas in search of gold. The Dutch arrived in 1605 and were quickly followed by the English, who established a factory in Makassar. In 1905 the entire island became part of the Dutch state colony of the Netherlands East Indies until Japanese occupation in World War II. Following the transfer of sovereignty in December 1949, Sulawesi became part of the federal United States of Indonesia, which in 1950 became absorbed into the unitary Republic of Indonesia.

Sulawesi's tough terrain, massive size (174,600 km²) and great marine tradtions, have combined to cause a wildly divergent set of peoples and cultures, speaking eight major languages and professing Muslim, Christian, Hindu and animist beliefs (not to mention various mixes thereof).

Islam is the majority religion in Sulawesi. The conversion of the lowlands of the south western peninsula in South Sulawesi to Islam occurred in the early 17th century. Most Sulawesi Muslims are Sunnis.

Christians form a substantial minority of about 19% on the island. Christians are concentrated on the tip of the northern peninsula around the city of Manado and around Poso in Central Sulawesi. The famous Toraja people of Tana Toraja in Central Sulawesi have largely converted to Christianity since Indonesia's independence.

Though most people identify themselves as Muslims or Christians, they often subscribe to local beliefs and deities as well. It is not uncommon for Christians to make offerings to local gods, goddesses, and spirits.

Sulawesi has been plagued by Muslim-Christian violence in recent years. The most serious violence occurred between 1999 and 2001 on the once peaceful island, with heavy involvement of Islamist militias such as Laskar Jihad. Over 1,000 people were killed in violence, riots, and ethnic cleansing that ripped through Central Sulawesi. In 2003, 13 Christian villagers were killed in the Poso District by unknown masked gunmen. And in 2005 three Christian schoolgirls were beheaded in Poso by Islamic militants. Riots erupted again in September 2006 in Christian dominated areas of Central Sulawesi.

Sulawesi's main port of entry is Makassar, which has frequent flights throughout the archipelago. Manado acts as a secondary hub, with some interesting connections eastward to Halmahera and Papua. Both airports are international airports with visitor-on-arrival facilities, with international flights to Kuala Lumpur from Makassar, and to Singapore from both airports.

The area around Tana Toraja is a fascinating one and well worth a visit. The Torajans are Christians but still maintain strong connections to their Indigenous culture and religion. Locals welcome visitors to take part in their elaborate funeral ceremonies which are interesting but involve animal sacrifices and are not for the squeamish.

Sulawesi cuisine is quite varied, but the best-known is Manadonese cuisine from the north, an interesting mix of Dutch influences, incredibly spicy chillies and unorthodox ingredients like bat and dog.